Staphylococcus aureus specific memory CD8 T cells in dairy cows (40.12)

Abstract

Abstract Staphylococcus aureus is a versatile pathogen that causes disease in both humans and animals. An increase in occurrence of nosocomial infections and chronic mastitis caused by antibiotic resistant strains warrants the need for an effective vaccine. This study assessed the presence of S. aureus specific memory T cells (Tm) in previously infected cows using CD14+ monocyte derived dendritic cells (DC). Results indicate that DC are able to uptake and recognize S. aureus antigens through various pattern recognition receptors (PRRs). Blocking of endocytic pathways using inhibitors confirmed S. aureus uptake by DC. S. aureus stimulated DC showed increased cell surface expression of MHC I and II and cytokine production suggesting activation and antigen presentation. An initial screening study for Tm in cows previously infected with S. aureus showed a significant increase in lymphocyte proliferation compared to control animals. To characterize the proliferating population of Tm, CFSE labeled lymphocytes were co-cultured with irradiated or live S. aureus stimulated autologous DC from previously infected cows identified as CD4, CD8 and WC1+ γδ T cells by flow cytometry. Proliferated CD4 and CD8 T cells were further characterized for memory markers, CD45RO and CD62L. Being the first study to show the presence of S. aureus specific CD8 Tm cells, our next step is to identify the S. aureus antigens that initiate T cell clonal expansion.